Conventionally, a shift-by-wire which electrically switches a shift range of an automatic transmission by using a switched reluctance motor (SR motor) is well known. When using the SR motor, it is necessary to associate a rotational position of the SR motor with the shift range. According to JP-2012-107657A (US 2012/0123653 A1), when the shift-by-wire is used, an initial position of the SR motor is learned at a time point that a power of a vehicle is turned on. That is, when the power is turned on, a controller of the shift-by wire learns the initial position in a specific shift range such as a P-range. In this case, the P-range is disposed at an end portion. Then, the controller drives the SR motor to move to the specific shift range based on the initial position.
However, according to JP-2012-107657A, when the power is turned on at a time point that the SR motor is placed at a position rather than the P-range, the initial position cannot be learned. Therefore, when the power is turned on at a time point that the SR motor is placed at a position rather than the P-range due to a momentary power cut, it is possible that the controller cannot drive the SR motor or switch the shift range.